An admission and an observation

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iknowjohnny
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Joined: Thu Apr 24, 2008 2:10 am
Location: los angeles

An admission and an observation

Post by iknowjohnny »

For the record i wanted to admit a mistake i made and an observation about a mod i did to my marshall style build. I think i posted about this anyways, but i can't remember the posts in which i talked about it. Anyways, i deleted the cathode follower and took the tone stack feed from the plate of the stage that was B4 the CF. I thought this sounded better, but i knew it meant i would now have to tweak the entire preamp to best suit this new change. at some point i nailed it and was thrilled with the tone. No matter what i did, if i changed a single thing between the input and the last stage B4 the TS, the magical tone i was getting would go away. Some how i seemed to have achieved the perfect balance. I haven't touched it since.

however, the one thing that had become apparent is that in a mix it did not come thru well enough. i don't want to use the word cut, but i guess thats the best word i can think of. It's more like the old blanket over the speaker thing.....just wasn't clear and up front in a mix. After trying many ways to add bightness in an attempt to remedy that it hit me that since this killer tone goes away when i change a single thing in the preamp up to the point B4 the TS that the deletion of the CF was probably NOT why i had this great tone and that it may be responsible for the lack of cut.

So as you have probably guessed, i added the CF stage back in and that did the trick ! so after touting how great the amp sounds with a plate fed TS, and after even asking why it is so many amps use a CF when mine benefited so much by removing it, i must now look you all straight in the eyes and say "DOH!!!!". :D It was NOT the deletion of the CF, it was the tweaks i did to the gain stages which did it, but in a way removing the CF was responsible for me finding that circuit balance because had i not done this i wouldn't have used some of the tweaks that worked so well because each on thier own i never liked B4. But with the plate fed stack they seemed to work better and that led me to a great gain stage setup. It's just amazing how many times i have discovered tweaks i thought were great only to later realize i'm full of......
Gibsonman63
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Location: Texas

Re: An admission and an observation

Post by Gibsonman63 »

That's always the quandry for me. I'll play through my amp the next day after a gig and I can't believe how thin and trebly it sounds... but add a solid kick drum and a bass guitar holding the bottom down and the overall sound is very balanced and everyone has thier own space in the mix.

I am never done tweaking an amp until it has been field tested.
iknowjohnny
Posts: 1070
Joined: Thu Apr 24, 2008 2:10 am
Location: los angeles

Re: An admission and an observation

Post by iknowjohnny »

I "field test" mine after every tweak. Actually, not at a gig but with music cranked to stage volume and play along. Not as good, but it does tell me how it will fare at a gig pretty well. I used to field test things at gigs but it took a gig just to test one simple change. this way i can tests dozens of things in a nite at home. Of course i never could till i moved to my current location where i can crank music like i never could b4. It's truly amazing how you can sit there and play and it sounds fantastic, then hit the button and start the CD/MP3/etc and play along and hear the tone change nite and day different. really makes tweaking an amp infinately easier than making one change, do a gig, make another, do a gig. When i did that it would take me a year to learn things about my tone that i can now determine in a day or 3. I rarely play out anymore either, so i'd never get anything doen w/o this method.
John_P_WI
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Location: Wisconsin

Re: An admission and an observation

Post by John_P_WI »

Just curious, when you rewired to a plate driven tone stack, did you use the spare triode as a gain stage, so you had 4 gain stages, or did you abandon it and keep the 3 gain stage structure, just plate driven tone un-buffered?
iknowjohnny
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Location: los angeles

Re: An admission and an observation

Post by iknowjohnny »

I abandoned it and was going to use it for a loop later on. So i see what you're saying....the change to a lower impedence source is why it sounded darker? How should i have done it from the plate?
John_P_WI
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Location: Wisconsin

Re: An admission and an observation

Post by John_P_WI »

I was just curious if the change in tone was from the addition of an extra gain stage and added harmonics from that.

I like plate driven tone stacks for high gain, and CF driven tone stacks for classic rock tones. Just another tonal color if you will.
iknowjohnny
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Joined: Thu Apr 24, 2008 2:10 am
Location: los angeles

Re: An admission and an observation

Post by iknowjohnny »

I can see that, as the amp is not really hi gain. It is subjective as to what amount of gain would be considered hi gain. I think it's on the verge of that but more classic rock gain levels except that it's coming from the preamp instead of the PA. About the same level as say a PV classic 30's distortion channel. So i guess i would agree with you because the darker nature of the plate driven stack would probably work well with true hi gain in keeping it from being too buzzy. anyways, thanks for the replies.
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jaysg
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Re: An admission and an observation

Post by jaysg »

I've got a preamp with a mosfet for the cathode follower. It's intended to be clean, and it serves the function. Years ago, somebody at Ampage did some experiementing in a Marshall and felt that you couldn't tell the difference between a tube and the mosfet, clean, dimmed, in between. If you hear it that way, you can get that triode back.
iknowjohnny
Posts: 1070
Joined: Thu Apr 24, 2008 2:10 am
Location: los angeles

Re: An admission and an observation

Post by iknowjohnny »

Naaa, i'm fine w/o it. I wanted to put a loop in just because i had an extra tube, but i don't want one that bad. Just figured since it's there...
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